Adubação foliar com líquido da casca do coco verde (LCCV) no melão amarelo: crescimento, produção e qualidade dos frutos

Abstract

Melon (Cucumis melo L.) cultivation stands out as one of the main agricultural activities in Northeast Brazil, requiring adequate nutritional management, with emphasis on potassium (K), to guarantee fruit quality. At the same time, the coconut agro-industry generates significant volumes of waste, including green coconut husk liquid (GCLL), a byproduct rich in salts and nutrients, but potentially polluting if disposed of improperly. This study aimed to evaluate the agronomic viability of using GCLL as a supplementary source of potassium fertilization via foliar application in the cultivation of the hybrid melon 'Meloro F1'. The experiment was conducted in a greenhouse, in a completely randomized design (CRD), testing six concentrations of the liquid (0%, 2.5%, 5.0%, 7.5%, 10.0%, and 12.5%), applied at 31, 38, 45, and 50 days after sowing (DAS). Vegetative growth parameters (height, stem diameter, and number of leaves), SPAD index, productivity, and post-harvest physicochemical quality of fruits (Brix, pH, firmness, and fruit morphometry) were evaluated. The results indicated that the application of LCCV did not promote phytotoxicity to the plants. Growth showed punctual responses, with a linear adjustment for stem diameter at 45 DAS and a quadratic adjustment at 67 DAS. There was no statistical difference between treatments for soluble solids content, firmness, and average fruit weight, but there was for peel thickness in the peduncular region. It is concluded that foliar fertilization with LCCV only influenced stem diameter, not significantly altering the SPAD index, productivity, or post-harvest fruit quality compared to conventional management. Although the dose that maximizes yield has not been identified, the absence of phytotoxicity up to a concentration of 12.5% ​​validates the application of LCCV as an agronomically safe and ecologically sustainable alternative for the disposal of the residue.